What can I do to prevent cold air from trickling out of the ceiling vents during cold months? When the heat isn't on, cold air infiltrates the ductwork and cascades into the room. The house is three years old and is heated by a heat pump. The duct work does not have any leaks that I know of. Is there any type of butterfly baffle or damper that could be installed at the entry point to the room and that would close when air is not flowing?